Kidney (Renal) Cysts


A cyst is a sac that is filled with clear fluid. The majority of renal cysts are simple cysts, each with a thin wall sac. Simple cysts are common, occurring in approximately half of patients above the age of 50 years. They do not generally cause symptoms or harm to the kidney.


The majority of simple cysts are discovered by chance when patients are having a scan for another reason; however, occasionally larger cysts can cause loin pain. It is not fully understood why and how do simple cysts form.

How are simple cysts treated?

There is no need to treat most simple cysts; large symptomatic cysts can be treated surgically with laparoscopic (keyhole) de-roofing of the cyst.



What are complex renal cysts?

Occasionally cysts are regarded as Complex cysts if they have thick walls, calcifications, septa (divisions) or with a mass in the middle. There is a risk that some of these cysts might be kidney cancers.


Complex cysts are classified according to how they look on CT scans using the Bosniak classifications system into five groups to determine the degree of complexity. The more complex is the cyst, the more the risk of being cancerous.



How are complex cysts treated?

This is dependent on many factors including your general health, the degree of complexity and size of the cyst. Treatment options include:


  • No treatment is required for the least complex cysts.


  • Surveillance with careful monitoring with regular scans for the intermediate complex cysts.







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Private Secretary Contact

Debbie Coleman

KIMS Hospital

Newnham Court Way



ME14 5FT

Tel: 01622 538173



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